Thermoplastic urethane elastometric alloys

ABSTRACT

Thermoplastic urethane elastomeric alloys are obtained by melt compounding at least one first component that is a polyurethane elastomer having at least one plasticizer reacted therein, this first component being formed by heating a reaction mixture comprising at least one isocyanate having a functionality of less than about 2.2, at least one long chain polyol, at least one chain extender and at least one plasticizer in specified amounts at a temperature of at least about 330° F. (165.6° C.), with at least one second component that is another thermoplastic elastomer not within the definition of the first component.

This application is a divisional of application Ser. No. 08/474,095,filed Jun. 7, 1995, now U.S. Pat. No. 5,516,857, which in turn is acontinuation of application Ser. No. 08/082,479, filed Jun. 25, 1993,now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to thermoplastic urethane elastomericalloys containing as a first component at least one polyurethaneelastomer and as a second composition at least one thermoplasticelastomer that is not within the definition of the first component.

Silicone has been used medically in various applications, e.g., pumps,but has been found to have a number of undesirable properties such aspoor abrasion resistance which results in particles flaking off and, inthe case of medical applications, accumulating in one or another organin the body, low tensile strength, poor flex fatigue, and poor barrierproperties. Styrene-butadiene-elastomers have been evaluated assubstitutes for silicone and are inexpensive and processable but lackexcellent tear resistance and tensile strength. There is a need formaterials that overcome the disadvantages of silicone.

U.S. Pat. No. 4,608,418 to Czerwinski et al. teaches hot melt urethanecompositions formed from a mixture of one or more polyisocyanates, oneor more hydroxyl terminated polyols, one or more chain extenders and oneor more plasticizers. A hot melt composition generally is one applied inthe molten state, at temperatures of about 250°-450° F. (121.1°-232.2°C.), and having a viscosity in that condition (Brookfield viscometer) ofless than about 50,000 cps, preferably less than about 25,000 cps. Whencooled to room temperature, such compositions are solids that areelastomeric in nature. These compositions are formed by heating thereactants at temperatures of at least about 330° F. (165.6° C.),preferably at about 350° to about 450° F. (176.7°-232.2° C.) for 2 or 3hours. The compositions of this patent have been found to be anexcellent first material for use in the present invention. Thedisclosure of the U.S. Pat. No. 4,608,418 patent is hereby incorporatedby reference.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide compositions havingproperties that are superior to those of silicones, rubbers and otherelastomeric materials. Another object is to provide compositions havingexcellent memory, excellent compression set at both room temperature andbody temperature, high tensile strength, excellent tear resistance,excellent softness, warm "feel", low modulus (which means easy tostretch and conforming to body parts and their movements), long flexurallife, dimensional stability and thermoplastic processability. A furtherobject is to provide compositions having preselected speed of recovery,or "snap" after deformation. Yet another object is to provide methodsfor preparing these compositions. These and other objects of the presentinvention will be apparent from the following description.

SUMMARY OF THE INVENTION

The first component of the compositions of the present invention isformed from a mixture of one or more polyisocyanates, one or morehydroxyl terminated long chain polyols, one or more chain extenders, andone or more plasticizers. The first component is formed by blending itsconstituent ingredients and heating the blended mixture at about 330° F.(165.6° C.) to about 450° F. (232.2° C.) for 2 or 3 hours. The secondcomponent of the compositions of the present invention is athermoplastic composition, preferably a second thermoplasticpolyurethane composition, not within the definition of the firstcomponent. Examples of suitable second component composition are apolyurethane not within the definition of the first component, apolyamide, a polyester, a polyether blocked amide, a copolymer ofethylene and vinyl acetate, a copolymer of ethylene and acrylic acid ormethacrylic acid, or a polymer of vinyl chloride. More than one speciesof each component may be present.

DETAILED DESCRIPTION

The first component of the urethane compositions of the presentinvention is, as indicated in U.S. Pat. No. 4,608,418, a thermoplastichot melt composition comprising a polyurethane having at least oneplasticizer reacted therein formed by heating a reaction mixturecomprising at least one isocyanate having a functionality less thanabout 2.2, at least one hydroxyl terminated long chain polyol, at leastone chain extender and at least one plasticizer at a temperature of atleast about 330° F., wherein said components are present in amounts thatare within the values of the following formula: ##EQU1## wherein Arepresents the equivalent weight of the long chain polyol x the molesthereof used; B represents the equivalent weight of the chain extender xthe moles thereof used; C represents the equivalent weight of theisocyanate used; and D represents the grams of plasticizer.

The process for preparing the first component of the urethanecompositions of the present invention generally is, as disclosed in U.S.Pat. No. 4,608,418, to heat a polyurethane formed from a mixture of atleast one isocyanate having a functionality less than about 2.2, atleast one long chain polyol, at least one chain extender and at leastone plasticizer at a temperature of at least about 330° F., wherein saidcomponents are present in an amount to meet the foregoing formula. Theurethane material of the first component is based on essentiallystoichiometric amounts of a diisocyanate (which insures that athermoplastic material results) having a functionality of 2.2 or less,preferably 2.15 or less and most preferably in the range of 2.0-2.1. Ifthe functionality is in excess of 2.2, or with certain isocyanates suchas MDI and HMDI close to 2.2, a thermosetting material results.Preferably the NCO/OH ratio in the reaction system is about 0.95 toabout 1.05 as at values substantially in excess of 1.05 the reactionproduct tend to be non-thermoplastic. Chain extending agents, compoundswhich carry at least two active hydrogen atoms per molecule andpreferably have a molecular weight of from about 52 to below 500, mostpreferably from about 62 to about 250, are included in the reactionmixture. These compounds react with the isocyanate groups of theprepolymer to produce high molecular weight polyurethanes andpolyurethane ureas by linking several isocyanate prepolymers.Plasticizers are also included in the reaction mixture. The plasticizermust be capable of being reacted into the polyurethane at temperaturesof about 330° F. (165.6° C.).

In accordance with a preferred process of forming the first component ofthe compositions of the present invention, the ingredients thereof areblended at the lowest possible temperature, the system is permitted toexotherm and, after the peak exotherm has been reached, the system isheated at about 330° F. to about 450° F. while agitating to complete thereaction. The reaction of the one or more plasticizers into the systemis substantially completed simultaneously with attainment of therequisite temperature of at least about 330° F. (165.6° C.). Based onexperience to date, the plasticizer cannot be extracted therefrom or isonly partially extractable by common organic solvents, e.g., hexane,gasoline, motor oil, and the like, at normal end use conditions for thefirst component absent the second component. It is also possible,however, to simply blend all of the components, permit the blend to curein situ, and then, prior to or during use, elevate the temperature to atleast about 330° F. Heating time varies greatly depending upon the formof the composition. For example, assuming a substantially completelycured thin film or layer thereof (that is, one that has been permittedto cure in situ in place or in a container for a substantial period oftime), results indicate that heating to at least about 330° F. (165.6°C.) for at least about two hours to form the resultant hot meltcomposition.

The second component of the compositions of the present invention is athermoplastic elastomer composition and can be another urethane notwithin the definition of the first component, a polyamide, a polyestersa polyether blocked amide, a copolymer of etheylene with vinyl acetate,a copolymer of ethylene and acrylic acid or methacrylic acid, or apolymer of vinyl chloride.

Preferred polyisocyanate compounds for the first component and for thesecond component as well if it is a urethane are 4,4'-diphenyl methanediisocyanate hereafter termed MDI, and4,4'-methylene-bis(cyclohexylisocyanate) hereafter termed HMDI, andisocyanates of the formula O═C═N-- D!--N═C═O where D is an aliphaticgroup of from 6 to 36 carbon atoms. Suitable long chain polyols arepolyester polyols, polycaprolactone polyols, polyether polyols, orpolycarbonate polyols.

The chain extending compounds are straight or branched chain aliphaticdihydroxy compounds of from 2 to about 10 carbon atoms, e.g., ethyleneglycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol,1,5-pentanediol, 2-methyl -1,4-butanediol, 1,6-hexanediol, and1,10-decanediol. A preferred chain extender is 1,4-butanediol.

Suitable plasticizers are, for example, butyl benzyl phthalate, dibutylphthalate, dioctyl phthalate, and dipropylene glycol dibenzoate. Apreferred plasticizer is butyl benzyl phthalate.

Compositions made in accordance with the teachings of U.S. Pat. No.4,608,418 can, of course, be used as the first component of thecompositions of the present invention. Examples of such compositionsinclude the following:

Lambda™C100-55, Lambda™ C101-35, Lambda™ C103-46, Lambda™ C200-65,Lambda™ C201-57, Lambda™ C210-50D, Lambda™ C301-75, Lambda™ C3300-80,Lambda™ C3300-85, Lambda™ L104-40 and Lambda™ L3300-90. Lambda is atrademark of Genesco. Lambda C101-35 is a thermoplastic MDI-based,polyester urethane elastomer formed with a long chain ethylene adipatepolyester diol having an average molecular weight (m.w.) of 1000 andhydroxyl number of 55. Lambda™ C100-55, LambdaTM C103-46, LambdaTMC200-65, Lambda™ C201-57, Lambda™ C210-50D and Lambda™ C301-75 areMDI-based polycaprolactone urethane elastomers, and L104-40 is anHMDI-based long chain polycaprolactone diol with an average m.w. of 3000and hydroxyl number of 37.4. LambdaTM L3300-80, Lambda™ L3300-85 andLambda™ L3300-90 are HMDI-based polyether urethane elastomers.

Commercially available urethane compositions that are usable as thesecond component of the compositions of the present invention includethe following:

TEXIN (Miles) thermoplastic polyurethane polyesters 480A, 591A, 688A,345D, 355D, 445D, 455D, 458D, 5187; TEXIN (Miles) polyurethanepolyethers 985A, 990A, and 970D; TEXIN (Miles) thermoplasticpolyurethanes 5187, 5286, 5265 and 5370; ESTANE (B.F. Goodrich)polyester-based polyurethanes 58144, 58271, 58277, 58300, 58887, and58863; and PELLETHANE (Dow) polyester polycaprolactone elastomer 2102;polytetramethylene glycol ether 2103; polyester polycaprolactone 2354,automotive grades; polyester polyadipate 2355; and polytetramethyleneglycol ether 2363, health care applications, thermoplastic 455 (Morton).

Examples of non-urethane thermoplastic compositions usable as the secondcomponent of the compositions of the present invention include thefollowing:

(a) polyamide resins, e.g., Versamid 930 and Henkel Macromelt 6238(Henkel);

(b) polyester resins, e.g., Hytrel 5556, 6356, 8538, and Emser IG(DuPont);

(c) polyether block amides, e.g., Pebax resins 2533, 3533, and 4033(Atochem);

(d) copolymers of ethylene and

(1) vinyl acetate, e.g., DuPont Elavax resins such as 265 and 205-W, andDuPont Hy-Elvaloy resins 965 and HP-441, or

(2) methacrylic acid, e.g., DuPont Nucryl resins; or

(e) polyvinyl chloride, e.g., Fleximer resins such as Geon 83741 (B.F.Goodrich).

The compositions of the present invention are prepared by mixing andmelt alloying or melt compounding at least one first component asdefined herein and at least one second thermoplastic elastomer notwithin the definition of the first component. The melt alloying or meltblending can be carried out in any conventional plastic and/or rubberprocessing equipment, e.g., extruder, continuous mixer, or banburyprocess equipment. The ranges of the two components can vary from 5-95%wt. % of one to 95-5 wt. % of the other, preferably from 15-85 wt. % ofone to 85-15 wt. % of the other, more preferably from about 20-80 wt. %of one to about 80-20 wt. % of the other, and most preferably from about30-70 wt. % of one to about 70-30 wt. % of the other.

End products made from the compositions of the present invention haveoutstanding properties:

1) Compression set performance--in their functional temperature range offrom room temperature to body temperature, compression set is between15-20 as determined by

2) Recovery performance--where performance measurement was the amount ofdrug delivered from the first deflection to the last, after over1,000,000 consecutive deflections, the diaphragm of a peristaltic pumpdelivered the same amount of drug after the last deflection as after thefirst. Gaskets are better than silicone in holding a negative pressureand in air barrier properties.

3) Elastic properties--these products have outstanding elasticproperties of recovery and snap back. After repeated elongation, 5cycles, to 200%, 250% and 300% elongation, the composition of example 1shows 100% recovery at 200% and 250% elongation and 95-100% recovery at300% elongation.

4) Low modulus--while having excellent recovery, elastic compression setproperties, the products have a low modulus compared to otherelastomers, especially other urethanes. That is, they are very easy tostretch and are very comfortable in accommodating to body movements.

5) Blood contact--the products pass USP Class VI blood contact test;they do not kill blood cells.

6) Tear resistance--outstanding for such a soft material.

7) Puncture resistance--outstanding for such a soft material.

8) Abrasion resistance--outstanding for such a soft material.

The following examples illustrate the present invention without,however, limiting the same thereto.

EXAMPLE 1

Materials: TEXIN 480A --thermoplastic MDI based, aromatic ester urethaneelastomer (Miles)

Lambda™ C101-35 --thermoplastic MDI based, aromatic ester urethaneelastomer formed with long chain ethylene adipate polyester diol havingaverage m.w. of 1000 and hydroxyl number of 55 (Genesco)

Two parts by weight of Texin 480A and one part by weight of C101-35 weremelt blended at temperatures between about 250° F. and 425° F.(121.1°-232.20°C.), preferably between about 250° F. and 390° F. (121°C.-199° C.). The material was then cooled and formed into particles forfurther processing as a thermoplastic elastomeric material into thedesired device, shape or configuration by, e.g. injection molding,extrusion and the like. The extruder temperature profile was: extruderthroat, water cooled 60°-80° F. (15.6°-26.7° C.) zones land 2, 385° F.(196.1° C.), zone 3, 365° F. (185.00 ° C.) and zone 4 360° F. (182.2°C.), adapter, 330° F. (165.6° C.), and die 330° F. (165.6° C.). Theproducts had outstanding abrasion resistance, tensile strength, punctureresistance and general toughness, and yet a low softness, 50 Shore A. Inaddition they had a lower than anticipated modulus, that is to say, theywere easily deformed where other materials were difficult to deform andhence unacceptable in applications requiring deformation. The productsalso had outstanding recovery properties after deformation, namely, 100%recovery when elongated 200-250% or less. The products also had anunexpectedly short time period for recovery of physical properties,i.e., the physical properties had returned to about 80-85% of theirmaximum ten hours after injection molding. In the case of conventionalurethanes, about 48 hours are permitted to elapse before testing.

EXAMPLE 2

Materials: TEXIN 480A--thermoplastic MDI based, aromatic ester urethaneelastomer (Miles)

Lambda™ C101-35--thermoplastic MDI based, aromatic ester urethaneelastomer (Genesco)

One part by weight of Texin 480A and three parts by weight of C101-35were treated to the substantially same conditions as described inexample 1 with similar results being obtained.

EXAMPLE 3

Materials: ESTANE 58300--thermoplastic MDI based, aromatic esterurethane elastomer (Goodrich)

Lambda™ C100-55--thermoplastic MDI based, aromatic ester urethaneelastomer (Genesco)

One part by weight of ESTANE 58300 and two parts by weight of C100-55were treated to the substantially same conditions as described inexample 1 with similar results being obtained.

EXAMPLE 4

Materials: ESTANE 58277--thermoplastic MDI based, aromatic esterurethaneelastomer (Goodrich)

Lambda™ C103-45--thermoplastic MDI based, aromatic ester urethaneelastomer (Genesco)

One part by weight of 58277 and two part by weight of C103-45 weretreated to the substantially same conditions as described in example 1with similar results being obtained.

EXAMPLE 5

Materials: Pebax 2533--thermoplastic MDI based, aromatic ester urethaneelastomer (Atochem)

Lambda™ C200-65 - thermoplastic MDI based, aromatic ester urethaneelastomer (Genesco)

One part by weight of Pebax 2533 and two parts by weight of C200-65 weretreated to the substantially same conditions as described in example 1with similar results being obtained.

EXAMPLE 6

Materials: TEXIN 480A --thermoplastic MDI based, aromatic ester urethaneelastomer (Miles)

Lambda™ C103-45--thermoplastic MDI based, aromatic ester urethaneelastomer (Genesco)

One part by weight of Texin 480A and two parts by weight of C103-45 weretreated to the substantially same conditions as described in example 1with similar results being obtained.

EXAMPLES 7-12

Following the procedures described herein, additional compositions ofthe present invention are prepared from the following materials:

7. Versamid 930--thermoplastic polyamide resin (Henkel), one part byweight

Lambda™ L104-40--HMDI-based long chain polycaprolactone diol (Genesco),one part by weight

8. Hytrel 5556--polyester resin (DuPont), three parts by weight

Lambda™ L3300-80-HMDI-based polyether urethane elastomer, two parts byweight

9. Elavax 265--vinyl acetate resin (DuPont), three parts by weight

Lambda™ C301-75-MDI-based polycaprolactone urethane elastomer, one partby weight

10. Geon 83741-polyvinyl chloride polymer (B.F. Goodrich), two parts byweight

Lambda™ C100-55-thermoplastic MDI based, aromatic ester urethaneelastomer, three parts by weight

11. TEXIN 985A -polyurethane polyether (Miles), seven, parts by weight

Lambda™ C103-45--thermoplastic MDI based, aromatic ester urethaneelastomer, three parts by weight

Although specific features of the invention are included in someembodiment and not others, it should be noted that each feature may becombined with any or all of the other features in accordance with theinvention.

In addition, it should be noted that the invention is not intended to belimited to the specific materials and construction described herein.

It should be understood that the foregoing description of the inventionis intended to be merely illustrative thereof, that the illustrativeembodiments are presented by way of example only, and that othermodifications, embodiments, and equivalents may be apparent to thoseskilled in the art without departing from its spirit. Having thusdescribed the invention, what we desire to claim and secure by LettersPatent is:

I claim:
 1. A composition containing:(a) from 5-95 wt. % of a firstcomponent of at least one first thermoplastic hot melt compositioncomprising a polyurethane having at least one phthalate plasticizerreacted therein formed by heating to a temperature of at least about330° F. a reaction mixture comprising at least one isocyanate having afunctionality less than about 2.2, at least one long chain polyol havingan average molecular weight of from about 1000 to about 3000, at leastone chain extender having a molecular weight of from about 52 to below500 and at least one plasticizer, wherein said ingredients are presentin amounts sufficient to meet the following formula: ##EQU2## wherein Arepresents the equivalent weight of the long chain polyol x the molesthereof used; B represents the equivalent weight of the chain extender xthe moles thereof used; C represents the equivalent weight of theisocyanate used; and D represents the grams of plasticizer, and b) from95-5 wt. % of a second component of at least one thermoplasticcomposition selected from the group consisting of a polyamide polyester,a polyether block amide, a copolymer of ethylene and vinyl acetate, acopolymer of ethylene and acrylic acid or methacrylic acid, or a polymerof vinyl chlorides said composition being prepared by melt mixing.
 2. Acomposition according to claim 1 wherein the isocyanate in the firstcomponent is MDI, HMDI or an isocyanate of the formula O═C═N-- D!--N═C═Owhere D is an aliphatic group of from 6 to 36 carbon atoms.
 3. Acomposition according to claim 1 wherein the long chain polyol in thefirst component is a polyester polyol, a polycaprolactone polyol, apolyether polyol, or a polycarbonate polyol.
 4. A composition accordingto claim 1 wherein the chain extender of the first component is a shortchain diol of from 2 to about 10 carbon atoms.
 5. A compositionaccording to claim 4 wherein the chain extender of the first componentis ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol,1,4-butanediol, 1,5-pentanediol, 2-methyl-1,4-butanediol,1,6-hexanediol, and 1,10-decanediol.
 6. A composition according to claim1 wherein the plasticizer is capable of being reacted into thepolyurethane at a temperature of about 330° F. (165.6° C.).
 7. Acomposition according to claim 6 wherein the plasticizer is butyl benzylphthalate, dibutyl phthalate, dioctyl phthalate, or dipropylene glycoldibenzoate.
 8. A composition according to claim 1 wherein the secondcomponent is a polyamide.
 9. A composition according to claim 1 whereinthe second component is a polyester.
 10. A composition according toclaim 1 wherein the second component is a polyether block amide.
 11. Acomposition according to claim 1 wherein the second component is acopolymer of ethylene and vinyl acetate.
 12. A composition according toclaim 1 wherein the second component is a copolymer of ethylene andacrylic acid or methacrylic acid.
 13. A composition according to claim 1wherein the second component is a polymer of vinyl chloride.
 14. Acomposition according to claim 1 wherein the first component is presentin an amount of from about 15 to about 85 wt. % and the second componentis present in an amount of from about 85 to about 15 wt. %, theisocyanate in the first component is MDI, HMDI or an isocyanate of theformula O═C═N-- D!--N═C═O where D is an aliphatic group of from 6 to 36carbon atoms, the long chain polyol in the first component is apolyester polyol, a polycaprolactone polyol, a polyether polyol, or apolycarbonate polyol, the chain extender is a short chain diol of from 2to about 10 carbon atoms, and the plasticizer is capable of beingreacted into the polyurethane at a temperature of about 330° F. (165.6°C.).
 15. A composition according to claim 1 wherein the first componentis present in an amount of from about 20 to about 80 wt. % and thesecond component is present in an amount of from about 80 to about 20wt. %.
 16. A composition according to claim 1 wherein the firstcomponent is present in an amount of from about 30 to about 70 wt. % andthe component is present in an amount of from about 70 to about 30 wt.%.
 17. A method of preparing a composition of claim 1 comprising meltcompounding at least one first component according to claim 1 with atleast one second component according to claim 1 at a temperature of atleast about 330° F. (165.6° C.).
 18. A method of preparing a compositionas described in claim 17, wherein said second component is a polymer ofvinyl chloride.